Cells in the nervous system are often highly interconnected; however, their firing times are synchronized during certain events such as gamma oscillations and theta oscillations. During these oscillations, crosscorrelations can show synchronization of spike times. However, when the cells are not synchronized, it is our hypothesis that there may be more complex interactions, such as generalized synchrony, that cannot be detected using linear analysis (i.e. cross correlation). These interactions may give a much richer understanding of the interactions between cells. Currently, no technique exists to detect these complex interactions in neurons. We intend to record from two pyramidal cells in the hippocampus simultaneously with and without glutamate antagonists. The glutamate antagonists increases synchrony between cells. Analysis to detect nonlinear functional relations between the firing patterns of the cells will be applied to the time series. We will use a technique called mutual prediction. It has been used to show interactions between single cells and the population activity in the stimulated cat spinal cord that linear techniques could not detect. This work will also develop a new technique for detecting nonlinear interactions by comparing patterns of interspike intervals using unstable periodic orbits. If a functional relationship is found between the spontaneous firing pattern of two cells when they are spontaneously firing, these techniques will be used, in a collaboration with another laboratory, to analyze interactions between two cells in the olfactory bulb and how they are effected by different odorants.